http://www.cs.colostate.edu/~cs160/.Spring16/assignments/P11.html

This programming assignment has four objectives:

Learn how to read and understand code.

Write code that fits into an existing game.

Keep the squirrels alive as long as possible.

Help the terriers hunt down the squirrels.

Description

The purpose of the assignment is to finish two Java classes that implement the behavior of 1) a squirrel that is trying to evade terriers, and 2) a terrier that feels compelled to chase squirrels. The game is played on a board, with some number of terriers and squirrels whose placement is determined by a file. The board is a two-dimensional array, with 'S' for Squirrel, 'D' for Terrier, 'T' for Tree, 'F' for Fence, and '-' for empty squares with Grass. The game engine reads the file specified on the command line, builds a user interface. Approximately every couple of seconds it asks each squirrel and terrier which way they want to move. You are going to code the behavior of both animals. Terrier behavior is defined in Terrier.java. Terriers always try to chase after the nearest squirrel and eat it. Terriers must avoid running into other terriers or going off the board, and they cannot climb trees or pass through Fences. Squirrel behavior is defined in Squirrel.java. Squirrels look for the closest terrier and always move in the opposite direction. Squirrel must avoid running into other squirrels or terriers, but they can pass through fences or climb trees. If they make it to a Tree, they are safe and disappear from the board. The game continues until all squirrels are safe or eaten, or for 30 iterations, whichever comes first. None of the supplied fields require that many iterations. The game engine reports all movements and significant events.

Instructions

NOTE: This assignment is complex, make sure and read the instructions carefully!

Part One

Create a project called P11, and download the following files:

Copy the code from UserInterface.java into P11/src.

Copy the code from GameEngine.java into P11/src.

Copy the code from AnimalInterface.java into P11/src.

Copy the code from Terrier.java into P11/src.

Copy the code from Squirrel.java into P11/src.

Copy the image file iconTerrier.png into the project.

Copy the image file iconSquirrel.png into the project.

Copy the image file iconMunch.png into the project.

Copy the image file iconFence.png into the project.

Copy the image file iconTree.png into the project.

Copy the image file iconGrass.png into the project.

Copy the image file squirrelPrints.png into the project.

Copy the image file dogPrints.png into the project.

Copy the data file SimpleGame.txt into the project.

Copy the data file TwoTerriers.txt into the project.

Copy the data file TwoSquirrels.txt into the project.

Copy the data file SquirrelEscape.txt into the project.

Copy the data file SquirrelFence.txt into the project.

Copy the data file SquirrelNightmare.txt into the project.

Only modify Squirrel.java and Terrier.java, do not modify other provided files.

Submit a P11.jar file with (only) Squirrel.java and Terrier.java.

Don't forget to put your name and the date in the comments.

After downloading and building the files, you should be able to run the GameEngine, but the Squirrel will always move right, and the Terrier will always move left. Both will soon go off the board, causing an exception. If GameEngine is not running at all, get some help in the lab.

Part Two

Next, modify the code in Terrier.java and Squirrel.java, which both implement the following interface:

public interface AnimalInterface{ public enum eMove { NO_MOVE, LEFT, UP_LEFT, UP, UP_RIGHT, RIGHT, DOWN_RIGHT, DOWN, DOWN_LEFT } // Find the closest squirrel or terrier public void findClosest(); // Report the closest position public int getClosestCol(); public int getClosestRow(); // Move the animal, according to the rules public void moveAnimal(); // Report the current position public int getCurrentRow(); public int getCurrentCol(); // Report the previous position public int getPreviousRow(); public int getPreviousCol(); } 

Complete the Squirrel object, as follows:

Write the findClosest method to find which Terrier is the closest. To do so you must scan the board from top to bottom and left to right, computing the Euclidean distance to each Terrier that you find. The Euclidean distance calculation is shown here.

Store the row and column of the closest terrier so that you can return it when getClosestRow and getClosestCol are called.

If more than one Terriers are at an equal distance, store the row and column for the first Terrier you find.

Copy the current position to the previous position.

Write the moveAnimal method in AnimalInterface. This move has several steps, which can all be included in the method, or you can add private methods for each step:

STEP 1) Select the move (of type eMove) which is in the exact opposite direction from the closest Terrier. For example, if the Terrier is left on the same row, move right. If the Terrier is below on the same column, move up. If the Terrier is above and right, move down and left. If the Terrier is below and right, move up and left, and so on.

STEP 2) Adjust the selected move (of type eMove) to avoid going off the board, running into a Terrier, or running into another Squirrel by carefully implementing the following behavior (in the order shown). You probably will want implement a private method to see if a particular move is valid.

If you are planning on moving DOWN_LEFT, but that move is not valid for one of the reasons above, move LEFT instead.

If you are planning on moving LEFT, but that move is not valid for one of the reasons above, move UP_LEFT instead.

If you are planning on moving UP_LEFT, but that move is not valid for one of the reasons above, move UP instead.

If you are planning on moving UP, but that move is not valid for one of the reasons above, move UP_RIGHT instead.

If you are planning on moving UP_RIGHT, but that move is not valid for one of the reasons above, move RIGHT instead.

If you are planning on moving RIGHT, but that move is not valid for one of the reasons above, move DOWN_RIGHT instead.

If you are planning on moving DOWN_RIGHT, but that move is not valid for one of the reasons above, move DOWN instead.

If you are planning on moving DOWN, but that move is not valid for one of the reasons above, move DOWN_LEFT instead.

If you get through adjusting the move as specified above, and the move is still not valid, set the move to NO_MOVE and return without updating the position.

STEP 3) Make the move by modifying the currentRow and currentCol based on the adjusted move. For example, if the move is DOWN, increment currentRow, if the move is LEFT, decrement currentCol, if the move is UP_RIGHT, decrement currentRow and increment currentCol, and so on.

To give you an idea of the scope of Squirrel.java, I wrote a method of ~15 actual lines to find the closest Terrier, ~20 lines to select the move, ~30 lines to adjust the move, ~10 lines to make the move, and ~10 lines for a private method to see if a particular move is valid. There is virtually all of the code required.

Complete the Terrier object, as follows:

Write the findClosest method to find which Squirrel is the closest, in the same manner as previously described.

If more than one Squirrels are at an equal distance, store the data for the first Squirrel you find.

Store the row and column of the closest Squirrel so that you can return it when getClosestRow and getClosestCol are called.

Copy the current position to the previous position.

Write the move method in AnimalInterface that selects the desired move for the Terrier, which should be in the direction of the closest Squirrel. For example, if the Squirrel is left on the same row, move left. If the Squirrel is below on the same column, move down. If the Squirrel is above and right, move up and right. If the Squirrel is below and right, move down and right, and so on.

Next you must avoid going off the board, or running into another Terrier, Fence, or Tree by carefully implementing the same algorithm as for the Squirrel, except that deciding whether a move is valid differs.

If you get through adjusting the move as specified above, and the move is still not valid, set the move to NO_MOVE and return without updating the position.

Otherwise, update the current position based on the move, before returning from moveAnimal.

Terrier.java is similar in size to Squirrel.java, and most of the code can be cloned, with minor changes.